1. Field
The present application relates to wireless communication, and in particular, to systems, methods and devices to enable management of frequency spectrum.
2. Background
The popularity of high-rate wireless data services is increasing the demand for access to available frequency spectrum by both organized and ad hoc wireless networks. The ability to satisfy the demand is often limited by a lack of available frequency spectrum that may be used for reliable communications within a geographic area. Given the limitations of the natural frequency spectrum and the licensed spectrum model adopted in most countries, there lies a challenge to accommodate the increasing demand for spectrum access.
In most countries, the available frequency spectrum has been divided into a number of licensed and unlicensed frequency bands. Wireless cellular networks and some television channel transmissions typically operate in a licensed frequency band. A network operator is often a primary user or licensee of a particular licensed band. As the primary user, the network operator, is allowed to exclude all other potential users, so that non-authorized sources of interference are minimized.
A drawback of the licensed spectrum model is that it can lead to under-utilization of a licensed frequency band. For example, there may be occasions when network utilization by the primary user is low, and/or there are geographic regions where there are few end users for the network operated by the primary. Simultaneously, communication on unlicensed bands may be congested with one or more users unable to access the unlicensed band for reliable communication.
Cognitive radio has been proposed to enable spectrum sharing. Spectrum sharing allows secondary users access to licensed portions of frequency spectrum when the primary user is not using a respective licensed frequency band at a given time and/or in a particular geographic location. Nevertheless, the primary user network has priority, and it is desirable to reduce, if not wholly eliminate, interference with primary user network communications. Hence, there lies a challenge for a secondary user to identify the presence of primary user network communication as quickly and efficiently as possible and vacate the respective licensed band as quickly as possible to mitigate interference with the primary user network.